David Kahn, Leading Historian of Codes and Code Breaking, Dies at 93

David Kahn, whose 1967 book, “The Codebreakers,” established him as the world’s pre-eminent authority on cryptology — the science of making and breaking secret codes — died on Jan. 24 in the Bronx. He was 93.

His son Michael said the death, at a senior-living facility, was from the long-term effects of a stroke in 2015.

Before Mr. Kahn’s book, cryptology itself was something of a secret. Despite an explosion in cryptological technology and techniques during the 20th century and the central role they played during World War II, the subject was typically overlooked by historians, if only because their possible sources were still highly classified.

“Codebreaking is the most important form of secret intelligence in the world today,” Mr. Kahn wrote in his book’s preface. “Yet it has never had a chronicler.”

Over the course of more than 1,000 pages, along with some 150 pages of notes, Mr. Kahn laid out cryptology’s long history, starting with ancient Egypt 4,000 years ago and proceeding through the French and American revolutions, the innovations wrought by the advent of the telegraph and telephone to the mid-20th century and the dawn of computer-assisted code breaking.